Let q and f(x) be an odd characteristic and an irreducible polynomial of degree m over Fq, respectively. Then, suppose that F(x)=xmf(x+x-1) becomes irreducible over Fq. This paper shows that the conjugate zeros of F(x) with respect to Fq form a normal basis in Fq2m if and only if those of f(x) form a normal basis in Fqm and the compart of conjugates given as follows are linearly independent over Fq, {γ-γ-1,(γ-γ-1)q, …,(γ-γ-1)qm-1} where γ is a zero of F(x) and thus a proper element in Fq2m. In addition, from the viewpoint of q-polynomial, this paper proposes an efficient method for checking whether or not the conjugate zeros of F(x) satisfy the condition.

Let V(φ) be a shift invariant subspace of L2(R) with a Riesz or frame generator φ(t). We take φ(t) suitably so that the regular sampling expansion : f(t) = f(n)S(t-n) holds on V(φ). We then find conditions on the generator φ(t) and various bounds of the perturbation {δ n }n∈Z under which an irregular sampling expansion: f(t) = f(n+ δn)Sn(t) holds on V(φ). Some illustrating examples are also provided.

In this letter, a highly linear 1.22 GHz current mirror based differential RF programmable gain amplifier (RFPGA) for digital TV tuner applications is proposed and implemented using 0.18-µm CMOS process. The fabricated RFPGA shows a maximum power gain of 9 dB, an OIP3 of 23.5 dBm, and an accurate dB-linear discrete gain step control while consuming 36 mA from a 1.8-V supply voltage.

Ge surfaces were irradiated by Ar+ ions at 600 eV with and without simultaneous supply of Ge or Al at room temperature. The surfaces ion-irradiated without any simultaneous metal supply were characterized by densely distributed conical protrusions. By contrast, various kinds of nanostructures were formed on the Ge surfaces ion-irradiated with a simultaneous metal supply. They featured cones and nanobelts with a flattened top for Ge supply cases, whereas they were characterized by the nanorods, nanobelts and nanowalls for Al supply cases. Very interestingly, most of the nanorods and nanobelts formed with an Al supply possessed a bottleneck structure. Thus, the Ge nanostructures were controllable in morphology by species and amount of simultaneously supplied metals.

In general, the spleen accompanied by abnormal abdomen is hypertrophied. However, if the spleen size is originally small, it is hard to detect the splenic enlargement due to abnormal abdomen by simply measure the size. On the contrary, the spleen size of a person having a normal abdomen may be large by nature. Therefore, measuring the size of spleen is not a reliable diagnostic measure of its enlargement or the abdomen abnormality. This paper proposes an automatic method to diagnose the splenic enlargement due to abnormality, by examining the boundary pattern of spleen in abdominal CT images.

A novel method for tailoring the beam profile of laser diodes that employs Lloyd's mirror interference is investigated. The beam profile in the vertical direction is controlled by inserting a GaAs mirror below the active layer. The experimentally obtained trends are successfully modeled by numerical calculations using Huygens' integral.

This paper introduces a new folding amplifier in a folding and interpolating 10-b ADC. The amplifier consists of current mirrors and differential stages. Only one current source is exploited in cascaded differential pairs, which reduces the power consumption significantly. In the folding circuit, the interpolation is implemented with a current division technique. An experiment of the amplifier in 10-b folding signal has been integrated in a single-poly four-metal 0.35 µm CMOS process. The simulation in 10-b folding ADC shows that power consumption is 225 mW at the sampling speed of 250 Msample/s and the power supply of 3.3 V. The preliminary experiment indicates the current steering folder and digital bits operate as expected.

When an IP Multicast network is constructed on a switch-based network, many IP Multicast packet broadcasts are generated, and these broadcasts cause trouble for all of the other kinds of communication. To solve this problem, implementing IGMP Snooping on various switches has been proposed. However, some switches have insufficient IP Multicast packet-handling capability. This problem is also mentioned in RFC4541. In this paper, we propose the IGMP Snooping Activator (ISA) mechanism as a way to solve the IP Multicast packet-handling problem. The ISA transmits dummy IGMP Queries to maintain the IP Multicast network, and it joins the flooding IP Multicast group to activate IGMP Snooping in switches that are unable to handle IP Multicast packets. The experimental evaluation shows the effectiveness of our proposed method: the network load decreases because of the method's effective restraint of IP Multicast packet flooding.

In this paper, we propose a method that uses Simulated Annealing (SA) to estimate the linear and nonlinear parameters of a closed-box loudspeaker system for implementing effective Mirror filters. The nonlinear parameters determined by W. Klippel's method are sometimes inaccurate and imaginary. In contrast, the proposed method can estimate the parameters with satisfactory accuracy due to its use of SA; the resulting impedance and displacement characteristics match those of an actual equivalent loudspeaker. A Mirror filter designed around these parameters can well compensate the nonlinear distortions of the loudspeaker system. Experiments demonstrate that the method can reduce the levels of nonlinear distortion by 5 dB to 20 dB compared to the before compensation condition.

Two-dimensional resonant optical scanners actuated by vertical electrostatic combs with a unique electrical isolation structure have been developed. The isolation on the movable frame surrounding 1 mm-diameter gimbal mirror is made by trenching the top silicon layer of an SOI wafer with leaving the thick bottom layers. Thanks to the large mass of the frame, the resonant frequencies range in 65.0-89.2 Hz for the frame and in 11.9-36.8 kHz for the mirror in a 4 mm4 mm chip. The resultant frequency ratio of the fast/slow axes reaches over 500 and such a high frequency ratio is utilized to display QVGA image by raster scanning of a laser beam.

Luby et al. derived evolution of degree distributions in residual graphs for irregular LDPC code ensembles. Evolution of degree distributions in residual graphs is important characteristic which is used for finite-length analysis of the expected block and bit error probability over the binary erasure channel. In this paper, we derive detailed evolution of degree distributions in residual graphs for irregular LDPC code ensembles with joint degree distributions.

The ηT pairing for supersingular elliptic curves over GF(3m) has been paid attention because of its computational efficiency. Since most computation parts of the ηT pairing are GF(3m) multiplications, it is important to improve the speed of the multiplication when implementing the ηT pairing. In this paper we investigate software implementation of GF(3m) multiplication and propose using irreducible trinomials xm+axk+b over GF(3) such that k is a multiple of w, where w is the bit length of the word of targeted CPU. We call the trinomials "reduction optimal trinomials (ROTs)." ROTs actually exist for several m's and for typical values of w = 16 and 32. We list them for extension degrees m = 97, 167, 193, 239, 317, and 487. These m's are derived from security considerations. Using ROTs, we are able to implement efficient modulo operations (reductions) for GF(3m) multiplication compared with cases in which other types of irreducible trinomials are used (e.g., trinomials with a minimum k for each m). The reason for this is that for cases using ROTs, the number of shift operations on multiple precision data is reduced to less than half compared with cases using other trinomials. Our implementation results show that programs of reduction specialized for ROTs are 20-30% faster on 32-bit CPU and approximately 40% faster on 16-bit CPU compared with programs using irreducible trinomials with general k.

For the construction of photonic crystal fiber (PCF) systems using their unique properties, a PCF coupler (PCFC) is one of the key components of the systems. The characteristics of the PCFC depend on the state of air holes in the tapered region of the PCFC because the state of air holes in the tapered region affects light propagation in the PCFC taper. In this paper, coupling characteristics of PCFCs were theoretically investigated. In PCFCs with air hole remaining tapers, we found that a smaller elongation ratio i.e. a stronger elongation is required to obtain optical coupling as an air hole pitch or a ratio of air hole diameter to pitch is larger. In PCFCs with air hole collapsed tapers, it was clarified that a dependence of extinction ratio on air hole collapsed elongation ratio is higher for smaller elongation ratio. It was also clarified that an air hole remaining PCFC has slow wavelength characteristics in extinction ratio compared to an air hole collapsed PCFC. Air hole remaining PCFCs and air hole collapsed PCFCs were fabricated using a CO2 laser irradiation technique. We could successfully control whether air holes in the PCFC taper were remaining or collapsed by adjusting the irradiated laser power in the elongation process of the PCFC fabrication. It was experimentally clarified that the air hole remaining PCFC has slow wavelength characteristics in extinction ratio compared to the air hole collapsed PCFC. The tendencies of the measured wavelength characteristics of PCFCs agree with those of numerical results.

This work presents an ultra-low-voltage ultra-low-power weak inversion composite MOS transistor. The steady state power consumption and the linear swing signal of the composite transistor are comparable to a single transistor, whereas presenting very high output impedance. This work also presents two interesting applications for the composite transistor; a 1:1 current mirror and an extremely low power temperature sensor, a thermistor. Both implementations are verified in a standard 0.35-µm TSMC CMOS process. The current mirror presents high output impedance, comparable to the cascode configuration, which is highly desirable to improve gain and PSRR of amplifiers circuits, and mirroring relation in current mirrors.

In this paper, we examine the effectiveness of clock control in protecting stream ciphers from a distinguishing attack, and show that this form of control is effective against such attacks. We model two typical clock-controlled stream ciphers and analyze the increase in computational complexity for these attacks due to clock control. We then analyze parameters for the design of clock-controlled stream ciphers, such as the length of the LFSR used for clock control. By adopting the design criteria described in this paper, a designer can find the optimal length of the clock-control sequence LFSR.

In this paper, we derive an upper bound for the average block error probability of a standard irregular low-density parity-check (LDPC) code ensemble under the maximum-likelihood (ML) decoding. Moreover, we show that the upper bound asymptotically decreases polynomially with the code length. Furthermore, when we consider several regular LDPC code ensembles as special cases of standard irregular ones over an additive white Gaussian noise channel, we numerically show that the signal-to-noise ratio (SNR) thresholds at which the proposed bound converges to zero as the code length tends to infinity are smaller than those for a bound provided by Miller et al.. We also give an example of a standard irregular LDPC code ensemble which has a lower SNR threshold than a given regular LDPC code ensemble.

Based on the channel properties of of the meteor burst communication, a kind of semi-irregular LDPC codes suitable for MBC is presented. Simulation results show that the application of this kind of semi-irregular LDPC codes in MBC yields better performance than the regular ones. Some theoretical analyses are given.

This paper describes a current-steering Digital-to-Analog Converter (IDAC) architecture with a novel switching scheme, designed for GPON Burst Mode Laser Drivers (BMLD) and realized in a 0.35 µm SiGe BiCMOS technology with 3.3 V power supply. The (4+6) segmented architecture of the proposed 10-bit IDAC is optimized for minimum DNL (Differential Nonlinearity). It combines a 4-bit MSBs (Most Significant Bits) unit-element sub-DAC and a 6-bit LSBs (Least Significant Bits) binary-weighted sub-DAC. A switching scheme based on this dedicated architecture yields a high monotony and a fast settling time. The linearity errors caused by systematic influences and random variations are reduced by the 2-D double centroid symmetrical architecture. Experimental results show that the DNL is below 0.5 LSB and that the settling time after the output current mirror is below 12 ns. Although the proposed IDAC architecture was designed for a BMLD chip, the design concept is generic and can be applied for developing other monotonic high-speed current-mode DACs.

Irregular LDPC codes can achieve better error rate performance than regular LDPC codes. However, irregular LDPC codes have higher error floors than regular LDPC codes. The Ordered Statistic Decoding (OSD) algorithm achieves approximate Maximum Likelihood (ML) decoding. ML decoding is effective to lower error floors. However, the OSD estimates satisfy the parity check equation of the LDPC code even the estimates are wrong. Hybrid decoder combining LLR-BP decoding algorithm and the OSD algorithm cannot also lower error floors, because wrong estimates also satisfy the LDPC parity check equation. We proposed the concatenated code constructed with an inner irregular LDPC code and an outer Cyclic Redundancy Check (CRC). Owing to CRC, we can detect wrong codewords from OSD estimates. Our CRC-LDPC code with hybrid decoder can lower error floors in an AWGN channel. In wireless communications, we cannot neglect the effects of the channel. The OSD algorithm needs the ordering of each bit based on the reliability. The Channel State Information (CSI) is used for deciding reliability of each bit. In this paper, we evaluate the Block Error Rate (BLER) of the CRC-LDPC code with hybrid decoder in a fast fading channel with perfect and imperfect CSIs where 'imperfect CSI' means that the distribution of channel and those statistical average of the fading amplitudes are known at the receiver. By computer simulation, we show that the CRC-LDPC code with hybrid decoder can lower error floors than the conventional LDPC code with hybrid decoder in the fast fading channel with perfect and imperfect CSIs. We also show that combining error detection with the OSD algorithm is effective not only for lowering the error floor but also for reducing computational complexity of the OSD algorithm.

Free-space optical communication systems can provide high-speed, improved capacity, cost effective and easy to deploy wireless networks. Experimental investigation on the next generation free-space optical (FSO) communication system utilizing seamless connection of free-space and optical fiber links is presented. A compact antenna which utilizes a miniature fine positioning mirror (FPM) for high-speed beam control and steering is described. The effect of atmospheric turbulence on the beam angle-of-arrival (AOA) fluctuations is shown. The FPM is able to mitigate the power fluctuations at the fiber coupling port caused by this beam angle-of-arrival fluctuations. Experimental results of the FSO system capable of offering stable performance in terms of measured bit-error-rate (BER) showing error free transmission at 2.5 Gbps over extended period of time and improved fiber received power are presented. Also presented are performance results showing stable operation when increasing the FSO communication system data rate from 2.5 Gbps to 10 Gbps as well as WDM experiments.